It has long been an object in the orthodontic industry to improve the aesthetic properties of orthodontic devices. Recently it has become apparent that a great demand exists for orthodontic devices which have a minimal visual impact when viewed by others. As a result, a new generation of orthodontic brackets which are difficult to visually observe, have become much more available. An example of such devices are orthodontic brackets made out of a ceramic or crystalline material having a substantially clear color or a color substantially identical to the tooth. While such orthodontic devices have contributed significantly to improving the asthetic appearance of orthodontic brackets, the elastomeric orthodontic tensioning devices used therewith, such as elastomeric O-rings and chains, detract or diminish the improvements such devices have provided due to their staining and/or discoloration. Clinical experience has indicated that such ligatures and chains, which are typically made of thermoplastic urethane, take on a discoloration or stained appearance within one to two weeks after application of the device. This detracts substantially from the overall appearance and benefits provided by the orthodontic brackets. With aesthetic type orthodontic brackets, discolored or stained ligatures have become more noticeable. While it is known that certain thermosetting urethanes provide stain resistant qualities, these urethanes have been found to lack the necessary strength to be used as orthodontic ligatures.
Applicants have invented an orthodontic ligature which provides increased resistance to discoloration or staining and the strength necessary for use as an orthodontic device.